For the first month alone, the Obama administration projected that nearly a half million people would sign up for the new health insurance markets, according to an internal memo obtained by The Associated Press. But that was before the markets opened to a cascade of computer problems. If the glitches persist and frustrated consumers give up trying, that initial goal, described as modest in the memo, could slip out of reach. The Sept. 5 memo, for Health and Human Services Secretary Kathleen Sebelius, lists monthly enrollment targets for each state and Washington, D.C., through March 31, the last day of the initial open enrollment period under President Barack Obama's health care overhaul.